It is known to produce N-acyl-acyloxy aromatic amines, e.g. 4-acetoxyacetanilide, by preparing the sodium salt of the corresponding N-acylhydroxy aromatic amine, e.g. N-acetyl-para-aminophenol (APAP), and reacting the sodium salt with the appropriate carboxylic acid anhydride, e.g. acetic anhydride. The N-acyl-hydroxy aromatic amine, e.g. APAP, used as the starting material for the foregoing reaction is in turn prepared by acylating the corresponding hydroxy aromatic amine, e.g. para-aminophenol, with an acylating agent such as an anhydride, e.g. acetic anhydride. However the latter reaction may cause problems such as the difficulty of mono-acylating the hydroxy aromatic amine, oligomerization of the hydroxy aromatic amine, and color body formation.
Furthermore, when APAP is produced from para-aminophenol, nitro-benzene typically is catalytically hydrogenated and concomitantly rearranged in the presence of a platinium catalyst to produce the para-aminophenol, presenting the problem of recovering the dissolved platinum catalyst.
It is also known to prepare APAP by hydrogenating 4-nitro-chlorobenzene to a 4-chloroaniline which is then reacted with aqueous KOH to form para-aminophenol. This is then acetylated as described previously to form the N-acetyl-para-aminophenol. This process is relatively complex requiring a fair number of reaction and purification steps. Moreover, the acetylation step in this process is believed to give rise to the same problems as occurs in the acetylation step of the nitrobenzene process described previously.
The preparation of hydroxy aromatic ketones by the Fries rearrangement of aromatic esters is well-known in the art. Thus, Lewis, U.S. Pat. No. 2,833,825 shows the rearrangement of phenyl or other aromatic esters to acylphenols or other hydroxy aromatic ketones using anhydrous hydrogen fluoride as catalyst. The examples of this patent are limited to the rearrangement of esters of higher fatty acids with the yields ranging from 55 to 95%.
Ganboa et al, Synthetic Communications 13(11), 941-944 (1983) show the production of acetanilide from acetophenone by refluxing in a solution of hydroxylamine hydrochloride. There is however no suggestion of the synthesis of N-acylacyloxy aromatic amines such as 4-acetoxyacetanilide (AAA) or of the synthesis of N-acylhydroxy aromatic amines such as N-acetyl-para-aminophenol (APAP).
The conversion of phenyl acetate or phenol and an acetylating agent, to 4-hydroxyacetophenone by a Fries rearrangement or Friedel-Crafts acetylation, respectively is shown in copending U.S. patent applications Ser. No. 616,989, filed June 4, 1984; Ser. No. 618,659, filed June 8, 1984 and now U.S. Pat. No. 4,524,217; Ser. No. 627,381, filed July 3, 1984 and now U.S. Pat. No. 4,560,789; Ser. No. 627,382, filed July 3, 1984 and now U.S. Pat. No. 4,568,763; Ser. No. 633,831, filed July 24, 1984; Ser. No. 633,832, filed July 24, 1984; and Ser. No. 642,981, filed Aug. 21, 1984, all owned by the same assignee as the present application. Previously there has been shown the conversion of 4-hydroxyacetophenone to the corresponding oxime, with the subsequent Beckmann rearrangement and accompanying acylation with a carboxylic acid anhydride to form an N-acyl-acyloxy aromatic amine. In such instances the specific Beckmann rearrangement catalysts were mineral acids such as sulfuric and hydrochloric acid; organic acids such a trifluoroacetic acid, para-toluenesulfonic acid, benzenesulfonic acid, and methane sulfonic acid; acidic ion-exchange resins such as Amberlyst.RTM. 15 or Nafion.RTM. 501 which are sulfonic acid ion-exchange resins produced by Rhom and Haas and Dupont, respectively; and thionylchloride.